Optical fiber connector and method of assembling the same on site

ABSTRACT

The present disclosure provides an optical fiber connector, comprising an integrated ferrule assembly and an integrated outer housing assembly, the ferrule assembly being adapted to be fitted into the housing assembly. The ferrule assembly at least comprises an inner housing, a spring, a multi-hole ferrule, a multi-fiber optical cable, a sleeve and a thermal shrinkable tube. The housing assembly at least comprises an outer housing, an outer tail tube and an outer protection cap. In the present disclosure, a plurality of components such as the inner housing, the spring, the multi-hole ferrule, multi-fiber optical cable, the sleeve, the thermal shrinkable tube and the like can be preassembled into an integrated ferrule assembly, and a plurality of components such as the outer housing, the outer tail tube, the outer protection cap and the like can be preassembled into an integrated outer housing assembly; then, a worker only needs to insert the integrated ferrule assembly into the integrated outer housing assembly on site, thereby completing assembling operation of the whole optical fiber connector conveniently and quickly.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.16/058,460, filed Aug. 8, 2018, now U.S. Pat. No. 10,473,867, which is acontinuation of U.S. application Ser. No. 15/324,971, filed Jan. 9,2017, now U.S. Pat. No. 10,073,224, which is a National Stage ofPCT/IB2015/055096, filed Jul. 6, 2015, which claims the benefit ofChinese Patent Application No. 201410324522.7 filed on Jul. 9, 2014 inthe State Intellectual Property Office of China the disclosures of whichare incorporated herein by reference in their entireties. To the extentappropriate a claim of priority is made to each of the above disclosedapplications.

BACKGROUND OF THE INVENTION Field of the Invention

The present disclosure relates to an optical fiber connector and amethod of assembling the same on site.

Description of the Related Art

In prior arts, a design of a multi-hole ferrule based enhancement modemulti-core optical fiber connector is accomplished by machining andassembling all elements in a controllable factory environment. When sucha design is to be applied in an application environment with a limitedspace (for example, an assembly needs to be passed through a pipe with alimited space), it is very difficult for the connector to be applied inthe environment with a limited space due to a relative larger head ofthe whole connector, and even an effective routing of the optical cableassembly cannot be achieved.

In prior arts, the enhancement mode multi-core optical fiber connectoris generally designed and manufactured as follows (a connectorcomprising a male ferrule is taken as an example, the same is true for aconnector comprising a female ferrule):

In a factory environment, a polished multi-hole ferrule (containingpreassembled optical fibers therein), an optical fiber protectionsleeve, an alignment pin (wherein a male ferrule comprises an alignmentpin, and a female ferrule comprises an alignment hole mating with thealignment pin) and a spring are fixed on an inner housing through aspring tail-holder, an optical cable strengthening component is fixed onthe inner housing by using an inner housing cover sheet and a sleeve sothat the optical cable and the inner housing are formed into a whole,then an outer housing is fitted over the inner housing, and a thermalshrinkable tube, a tail sleeve, an alignment insert, an outer protectionhousing and a seal ring are assembled, thereby forming a completeenhancement mode multi-core optical fiber connector.

The enhancement mode multi-core optical fiber connector in prior artshas the following defects:

a) it is not easy to pass the connector through a pipe on site due toits large dimension, particularly when the pipe has a limited space,which makes a routing operation of the optical cable difficult, or evenimpossible;

b) if a method of splicing a tail fiber for the enhancement modemulti-core optical fiber connector is used, that is, only the opticalcable is passed through the pipe on site, and then a tail fiberprefabricated in the factory environment for the enhancement modemulti-core optical fiber connector is spliced to the optical cableoutside the pipe. Although connection of the optical cable can beachieved by using this method, it is hard to ensure the splicingconnection has an uniform optical quality, this is because duringsplicing, the multi-core optical fiber has a relatively complicatedstructure and there are a number of uncertainties (e.g., dust or thelike) in a field (mostly, outdoor) environment. Moreover, atechnician/engineer who carries out the splicing operation should have ahigh level operant skill, the operation is time-consuming and therebythe cost in assembling is high. What is more important is that theuncertainty of the operation leads to a risk of reducing reliability ofthe connector;

c) no protection cap is mounted on the ferrule, thus, a front endsurface of the ferrule and a front end surface of the optical fibers inan internal bore of the ferrule can be damaged easily; and

d) all components composing the optical fiber connector need to beassembled one by one on site, the assembling is time-consuming, andtherefore it is inconvenient for a quick installation.

SUMMARY OF THE INVENTION

The present invention is aimed to overcome or alleviate at least oneaspect of the above mentioned problems and disadvantages.

An object of the present disclosure is to provide an optical fiberconnector, which can be quickly assembled on site.

According to one aspect of the present disclosure, there is provided anoptical fiber connector, comprising:

an integrated ferrule assembly composed of at least:

-   -   an inner housing;    -   a spring mounted in the inner housing;    -   a multi-hole ferrule mounted on a front end of the inner housing        and compressing the spring;    -   a multi-fiber optical cable with an end thereof inserted into        the inner housing from a rear end of the inner housing, a        plurality of optical fibers at the end being fixed in a        plurality of through holes of the ferrule;    -   a sleeve mounted on the rear end of the inner housing and        cooperating with the inner housing to fix a strengthening        element which is located at one end of the cable on the rear end        of the inner housing; and    -   a thermal shrinkable tube thermally shrunk over the sleeve and a        section of the cable exposed from the sleeve; and

an integrated outer housing assembly composed of at least:

-   -   an outer housing;    -   an outer tail tube connected to a rear end of the outer housing;        and    -   an outer protection cap hermetically connected to a front end of        the outer housing,

wherein the integrated ferrule assembly is adapted to be fitted in theintegrated outer housing assembly.

According to one exemplary embodiment of the present disclosure, theoptical fiber connector is a female connector; and the housing assemblyfurther comprises a seal ring, the outer protection cap is threaded ontoan outer wall of the front end of the outer housing, and the seal ringis pressed between the outer protection cap and the outer housing,thereby sealing an interface between the outer protection cap and theouter housing.

According to a further exemplary embodiment of the present disclosure,the optical fiber connector is a male connector, and the housingassembly further comprises a screw nut fitted over the outer housing andthreaded with the outer protection cap, and a seal ring pressed betweenthe outer protection cap and the outer housing, thereby sealing aninterface between the outer protection cap and the outer housing.

According to a further exemplary embodiment of the present disclosure,an annular seal ring is fitted over the sleeve so that when the outerhousing of the optical fiber connector is fitted on the ferruleassembly, the annular seal ring is pressed by the outer housing of theoptical fiber connector, thereby sealing an interface between the outerhousing of the optical fiber connector and the ferrule assembly.

According to a further exemplary embodiment of the present disclosure,an annular positioning recess is formed in the sleeve, and the annularseal ring is arranged in the positioning recess.

According to a further exemplary embodiment of the present disclosure,the ferrule assembly further comprises an inner tail sleeve fixed on therear end of the inner housing, thermal shrinkable tube is thermallyshrunk over the inner tail sleeve, and cooperates with the inner tailsleeve to form a lateral pulling prevention device for preventing theoptical cable being affected by a lateral pulling force.

According to a further exemplary embodiment of the present disclosure,the ferrule assembly further comprises an optical fiber protectionsleeve which is embedded in a mounting groove at a rear end of themulti-hole ferrule, and through which the plurality of optical fiberspass.

According to a further exemplary embodiment of the present disclosure,the multi-hole ferrule is a male ferrule, and the ferrule assemblyfurther comprises an alignment pin mating with an alignment hole in afemale ferrule, the alignment pin being fitting in a mounting hole ofthe multi-hole ferrule and projected from a front end of the multi-holeferrule.

According to a further exemplary embodiment of the present disclosure,the multi-hole ferrule is a female ferrule, in which an alignment holeis formed to mate with an alignment pin of a male ferrule.

According to a further exemplary embodiment of the present disclosure,the inner housing comprises a first half-housing and a secondhalf-housing which are separated from each other and are capable ofbeing assembled together.

According to a further exemplary embodiment of the present disclosure,the first half-housing and the second half-housing are assembledtogether through a first snapping mechanism.

According to a further exemplary embodiment of the present disclosure,the first snapping mechanism comprises: a first elastic snapping buckleformed on one of the first half-housing and the second half-housing; anda first snapping recess formed in the other one of the firsthalf-housing and the second half-housing.

According to a further exemplary embodiment of the present disclosure,two first positioning features, which cooperate with each other forpreventing the first half-housing and the second half-housing from beingassembled together in a misalignment state, are formed on the firsthalf-housing and the second half-housing, respectively.

According to a further exemplary embodiment of the present disclosure,the first positioning features comprise: a first positioning protrusionformed on one of the first half-housing and the second half-housing; anda first positioning recess formed on the other one of the firsthalf-housing and the second half-housing.

According to a further exemplary embodiment of the present disclosure,the inner housing and the outer housing are assembled together through asecond snapping mechanism.

According to a further exemplary embodiment of the present disclosure,the second snapping mechanism comprises: a second elastic snappingbuckle formed on one of an outer wall of the inner housing and an innerwall of the outer housing; and a second snapping recess formed in theother one of the outer wall of the inner housing and the inner wall ofthe outer housing.

According to a further exemplary embodiment of the present disclosure,two second positioning features, which cooperate with each other forpreventing the inner housing and the outer housing from being assembledtogether in a misalignment state, are formed on the outer wall of theinner housing and the inner wall of the outer housing, respectively.

According to a further exemplary embodiment of the present disclosure,the second positioning features comprise: a second positioningprotrusion formed on one of the outer wall of the inner housing and theinner wall of the outer housing; and a second positioning recess formedin the other one of the outer wall of the inner housing and the innerwall of the outer housing.

According to a further exemplary embodiment of the present disclosure,the optical fiber connector is a female connector or a male connector,and the second positioning feature of the female connector mismatcheswith the second positioning feature of the male connector so as toprevent the outer housing of the male connector from being mounted onthe inner housing of the female connector in error, or to prevent theouter housing of the female connector from being mounted on innerhousing of the male connector in error.

According to a further exemplary embodiment of the present disclosure,the ferrule assembly further comprises a ferrule protection cap, whichis fitted over a front end surface of the ferrule so as to cover frontend surfaces of the optical fibers in an internal bore of the ferruleand at least a part of a mating region of a front end surface of theferrule mating with a mating ferrule, so that the front end surfaces ofthe optical fibers and the at least a part of the mating region of thefront end surface of the ferrule are isolated from external environment.

According to a further exemplary embodiment of the present disclosure,the ferrule protection cap comprises: a body portion including a matingend surface mating with the front end surface of the ferrule; and anelastic tail portion connected to a side of the body portion facing tothe mating end surface and extending by a predetermined length in adirection of axis of the optical fibers.

According to a further exemplary embodiment of the present disclosure, areceiving recess is formed in the mating end surface of the ferruleprotection cap, and the front end surfaces of the optical fibers arehermetically received within the receiving recess when the ferruleprotection cap is fitted over the front end surface of the ferrule.

According to a further exemplary embodiment of the present disclosure,the front end surface of the ferrule is formed at a predetermined anglewith respect to axes of the optical fibers, and the mating end surfaceof the ferrule protection cap is formed at an angle complementary tothat of the front end surface of the ferrule.

According to a further exemplary embodiment of the present disclosure,when the ferrule is a male ferrule, the mating end surface of theferrule protection cap is formed therein with an assembling hole formating with the alignment pin of the male ferrule; and when the ferruleis a female ferrule, the mating end surface of the protection cap isformed thereon with an assembling pin for mating with the alignment holeof the female ferrule.

According to a further exemplary embodiment of the present disclosure, areceiving hole for mating with the ferrule is formed in the outerhousing of the optical fiber connector; and the ferrule protection capis configured to be capable of passing through the receiving hole of theoptical fiber connector.

According to a further exemplary embodiment of the present disclosure, adimension of the ferrule protection cap in a direction perpendicular tothe axes of the optical fibers is smaller than that of the ferrule inthe direction perpendicular to the axes of the optical fibers.

According to a further exemplary embodiment of the present disclosure,when the outer housing of the optical fiber connector is fitted on theferrule assembly, the elastic tail portion of the ferrule protection capextends out from the outer housing so as to facilitate removal of theferrule protection cap after the outer housing is fitted on ferruleassembly.

According to a further exemplary embodiment of the present disclosure,the elastic tail portion of the ferrule protection cap is a corrugatedelastic component, an elastic component in the form of a spring or anelastic component in the form of an elastic sheet.

According to another aspect of the present disclosure, there is provideda method of assembling an optical fiber connector on site, comprisingsteps of:

providing the ferrule assembly as defined in any of precedingembodiments;

providing a traction component and hermetically connecting the tractioncomponent to the ferrule assembly so as to seal the ferrule of theferrule assembly within the traction component;

passing the ferrule assembly through an elongated pipe by towing thetraction component;

removing the traction component from the ferrule assembly;

providing the housing assembly defined in any one of precedingembodiments; and

fitting the ferrule assembly into the housing assembly, thereby formingan integrated optical fiber connector.

According to one exemplary embodiment of the present disclosure, theferrule assembly comprises a ferrule protection cap fitting over a frontend surface of the ferrule; and when the traction component ishermetically connected to the ferrule assembly, the traction componentholds the ferrule protection cap of the ferrule assembly on the ferruleso as to prevent the ferrule protection cap from being disengaged fromthe ferrule when the ferrule assembly is towed through the pipe.

According to a further exemplary embodiment of the present disclosure,the traction component is threaded on the inner housing of the ferruleassembly; and when the traction component is threaded on the innerhousing of the ferrule assembly, an annular seal ring on the sleeve ofthe ferrule assembly is pressed by the traction component so as to sealan interface between the traction component and the ferrule assembly.

According to a further exemplary embodiment of the present disclosure,the traction component is a cylindrical component having a closed endand an open end, the cylindrical component fitting over the innerhousing of the ferrule assembly.

According to a further exemplary embodiment of the present disclosure,an external thread is formed on an outer wall of the inner housing ofthe ferrule assembly, and an internal thread is formed on an inner wallof the traction component and configured to be connected with theexternal thread.

According to a further exemplary embodiment of the present disclosure, aconnection portion is formed on an outer side of the closed end of thetraction component and connected with a traction rod or a traction cord,so that the traction assembly is driven through the pipe by pulling orpushing the traction rod or traction cord.

According to a further exemplary embodiment of the present disclosure,an inner wall of the traction component is pressed on an elastic tailportion of the ferrule protection cap, so that the ferrule protectioncap is elastically held on the ferrule.

According to a further exemplary embodiment of the present disclosure,an outer diameter of the traction component is substantially the same asthat of the thermal shrinkable tube.

In embodiments of the present disclosure, a plurality of components,such as the inner housing, the spring, the multi-hole ferrule, themulti-fiber optical cable, the sleeve, the thermal shrinkable tube andthe like, can be preassembled into an integrated ferrule assembly, and aplurality of components, such as the outer housing, the outer tail tube,the outer protection cap and the like, can be preassembled into anintegrated outer housing assembly; then, a worker only needs to insertthe integrated ferrule assembly into the integrated outer housingassembly on site, thereby the assembling operation of the whole opticalfiber connector can be completed conveniently and quickly.

Further, the integrated ferrule assembly, which has a smaller volume,can easily be passed through an elongated pipe, and after being passedthrough the pipe, the integrated ferrule assembly can be convenientlyfitted into the integrated outer housing assembly, so as to form acomplete multi-core optical fiber connector.

Furthermore, in embodiments of the present disclosure, when the ferruleassembly fitted with the ferrule protection cap is passed through theelongated pipe or is fitted into the integrated outer housing assembly,the front end surface of the ferrule and the front end surfaces of theoptical fibers can be effectively protected from being damaged fromoutside.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present inventionwill become more apparent by describing in detail exemplary embodimentsthereof with reference to the accompanying drawings, in which:

FIG. 1 is a schematic exploded view showing a ferrule assembly accordingto one exemplary embodiment of the present disclosure;

FIG. 2 is an assembly diagram showing a ferrule assembly according toone exemplary embodiment of the present disclosure;

FIG. 3 is a schematic exploded view showing a traction assemblyaccording to one exemplary embodiment of the present disclosure;

FIG. 4 is an assembly diagram showing a traction assembly according toone exemplary embodiment of the present disclosure;

FIG. 5 is a partially cross sectional view of the traction assemblyshown in FIG. 4, showing a ferrule protection cap;

FIG. 6 is a schematic exploded view showing an inner housing of theferrule assembly shown in FIG. 1;

FIG. 7 is an assembly diagram showing the inner housing of the ferruleassembly shown in FIG. 1;

FIG. 8 is a schematic exploded view showing an optical fiber connectoraccording to one exemplary embodiment of the present disclosure;

FIG. 9 is a schematic diagram showing a snapping mechanism between anouter housing and the inner housing of the optical fiber connector shownin FIG. 8;

FIG. 10 is a schematic diagram showing a state in which the ferruleprotection cap of the ferrule assembly shown in FIG. 8 is passed througha receiving hole of the outer housing of the optical fiber connector;

FIG. 11 is a schematic diagram showing a positioning structure forpreventing an error mounting between an inner housing and an outerhousing of a female connector;

FIG. 12 is a schematic diagram showing a positioning structure forpreventing an error mounting between an inner housing and an outerhousing of a male connector;

FIG. 13 is a partially cross sectional view of an assembled opticalfiber connector according to one exemplary embodiment of the presentdisclosure, showing the ferrule protection cap;

FIG. 14 is a schematic enlarged view showing the ferrule protection capand the multi-hole ferrule shown in FIG. 1;

FIG. 15 is a schematic diagram showing an operation of assembling theferrule protection cap and the multi-hole ferrule shown in FIG. 1;

FIG. 16a is a schematic exploded view showing a housing assembly of afemale connector;

FIG. 16b is an assembly diagram showing the housing assembly of thefemale connector;

FIG. 17a is a schematic diagram showing the ferrule assembly and thehousing assembly of the female connector;

FIG. 17b is an assembly diagram showing the female connector formed byassembling the ferrule assembly and housing assembly shown in FIG. 17 a;

FIG. 18a is a schematic exploded view showing a housing assembly of amale connector;

FIG. 18b is an assembly diagram showing the housing assembly of the maleconnector;

FIG. 19a is a schematic diagram showing the ferrule assembly and thehousing assembly of the male connector; and

FIG. 19b is an assembly diagram showing the male connector formed byassembling the ferrule assembly and housing assembly shown in FIG. 19 a.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Exemplary embodiments of the present invention will be describedhereinafter in detail with reference to the attached drawings, whereinthe like reference numbers refer to the like elements. The presentinvention may, however, be embodied in many different forms and shouldnot be construed as being limited to the embodiment set forth herein;rather, these embodiments are provided so that the present inventionwill be thorough and complete, and will fully convey the concept of thedisclosure to those skilled in the art.

In the following detailed description, for purposes of explanation,numerous specific details are set forth in order to provide a thoroughunderstanding of the disclosed embodiments. It will be apparent,however, that one or more embodiments may be practiced without thesespecific details. In other instances, well-known structures and devicesare schematically shown in order to simplify the drawing.

According to one general inventive concept of the present invention,there is provided a ferrule protection cap 190 for an optical fiberferrule, the ferrule protection cap comprising: a body portion 191comprising a first side and a second side opposite to each other in afirst direction, the first side of the body portion 191 being mounted ona front end of a ferrule 110; and an elastic tail portion 192 connectedto the second side of the body portion 191 and extending by apredetermined length in the first direction.

FIG. 1 is a schematic exploded view showing a ferrule assembly accordingto one exemplary embodiment of the present disclosure; FIG. 2 is anassembly diagram showing a ferrule assembly according to one exemplaryembodiment of the present disclosure; FIG. 14 is a schematic enlargedview showing the ferrule protection cap and the multi-hole ferrule shownin FIG. 1; and FIG. 15 is a schematic diagram showing an operation ofassembling the ferrule protection cap and the multi-hole ferrule shownin FIG. 1

As shown in FIGS. 1-2 and FIGS. 14-15, in the illustrated embodiment,the ferrule 110 is a multi-hole ferrule, and the ferrule protection cap190 is configured to be fitted over the multi-hole ferrule. However, thepresent disclosure is not limited to the illustrated embodiments, theferrule protection cap may be modified so as to be fitted over asingle-hole ferrule; for example, the body portion 191 of theillustrated ferrule protection cap 190 can be modified into a sleeve; assuch, the body portion 191 in the form of a sleeve may be directlyfitted over a front end of the single-hole ferrule.

As shown in FIGS. 1-2 and FIGS. 14-15, the ferrule protection cap 190mainly comprises the body portion 191 and the elastic tail portion 192.The body portion 191 comprises the first side and the second sideopposite to each other in the first direction (when the ferruleprotection cap 190 is fitted over the ferrule 110, the first directionis parallel to a direction of an axis of an optical fiber), the firstside of the body portion 191 is mounted on the front end of the ferrule110. The elastic tail portion 192 is connected to the second side of thebody portion 191 and extends by the predetermined length in the firstdirection.

As shown in FIGS. 1-2 and FIGS. 14-15, the body portion 191 covers frontend surfaces of the optical fibers 102 in an internal bore of theferrule 110 and at least a part of a mating region of a front endsurface 111 of the ferrule 110 mating with a mating ferrule, so that thefront end surface of the optical fibers 102 and the at least a part ofthe mating region of the front end surface 111 of the ferrule 110 areisolated from external environment.

As shown in FIGS. 1-2 and FIGS. 14-15, the body portion 191 and theferrule 110 are assembled together through a shaft-hole fitting.

As shown in FIGS. 1-2 and FIGS. 14-15, the body portion 191 comprises amating end surface 195 mating with the front end surface 111 of theferrule 110; the mating end surface 195 of the body portion 191 isprovided with an assembling hole/pin to mate with an alignment pin/holeof the front end surface 111 of the ferrule 110, and the body portion191 and the ferrule 110 are assembled together by mating the alignmentpin/hole with the assembling hole/pin.

As shown in FIGS. 1-2 and FIGS. 14-15, a receiving recess 193 is formedin the mating end surface 195 of the ferrule protection cap, so thatwhen the ferrule protection cap 190 is fitted over the front end surface111 of the ferrule 110, the front end surfaces of the optical fibers 102in the internal bore of the ferrule 110 are hermetically received withinthe receiving recess 193.

As shown in FIGS. 1-2 and FIGS. 14-15, the front end surface 111 of theferrule 110 is formed at a predetermined angle to axes of the opticalfibers, and the mating end surface 195 of the ferrule protection cap 190is formed at an angle complementary to an angle of the front end surface111 of the ferrule 110.

As shown in FIGS. 1-2 and FIGS. 14-15, the elastic tail portion 192 ofthe ferrule protection cap 190 may be a corrugated elastic component, anelastic component in the form of a spring, or an elastic component inthe form of an elastic sheet.

As shown in FIGS. 1-2 and FIGS. 14-15, when the ferrule protection cap190 is fitted over the ferrule 110, the ferrule protection cap 190 canbe passed through a receiving hole 390 in an outer housing 300 of theconnector for receiving the ferrule 110.

According to another general inventive concept of the present invention,there is provided a ferrule assembly 1000, comprising: an inner housing150; a spring 140 mounted in the inner housing 150; a multi-hole ferrule110 mounted on a front end of the inner housing 150 and compressing thespring 140; a multi-fiber optical cable 101 with an end thereof insertedinto the inner housing 150 from a rear end of the inner housing 150, aplurality of optical fibers 102 at this end being fixed in a pluralityof through holes of the ferrule 110; a sleeve 160 mounted on the rearend of the inner housing 150 and cooperating with the inner housing 150to fix a strengthening element 103 which is located at one end of thecable 101 on the rear end of the inner housing 150; and a thermalshrinkable tube 180 thermally shrunk over the sleeve 160 and a sectionof the cable 101 exposed from the sleeve 160. The ferrule assembly 1000is an independent integral component separated from the outer housing300 of the optical fiber connector, and the outer housing 300 of theoptical fiber connector can be fitted over the ferrule assembly 1000.

FIG. 1 is a schematic exploded view showing a ferrule assembly accordingto one exemplary embodiment of the present disclosure. FIG. 2 is anassembly diagram showing a ferrule assembly according to one exemplaryembodiment of the present disclosure.

As shown in FIG. 1 and FIG. 2, the illustrated ferrule assembly 1000 areassembled by a plurality of separate components, except for the outerhousing 300 and an outer tail tube 400 (see FIG. 8), and the ferruleassembly 1000 comprises: an inner housing 150; a spring 140 mounted inthe inner housing 150; a multi-hole ferrule 110 mounted on a front endof the inner housing 150 and compressing the spring 140; a multi-fiberoptical cable 101 with an end thereof inserted into the inner housing150 from a rear end of the inner housing 150, a plurality of opticalfibers 102 at this end being fixed in a plurality of through holes ofthe ferrule 110; a sleeve 160 mounted on the rear end of the innerhousing 150 and cooperating with the inner housing 150 to fix astrengthening element 103 which is located at one end of the cable 101on the rear end of the inner housing 150; a thermal shrinkable tube 180thermally shrunk over the sleeve 160 and a section of the cable 101exposed from the sleeve 160; an inner tail sleeve 170 fixed on the rearend of the inner housing 150, the thermal shrinkable tube 180 beingthermally shrunk over the inner tail sleeve 170 and cooperating with theinner tail sleeve 170 to form a lateral pulling prevention device forpreventing the optical cable being affected by a lateral pulling force;an optical fiber protection sleeve 130, which is embedded in a mountinggroove (not shown) at a rear end of the multi-hole ferrule 110, andthrough which the plurality of optical fibers 102 pass; and a ferruleprotection cap 190 fitted over a front end surface 111 of the ferrule110 so as to cover front end surfaces of the optical fibers 102 in aninternal bore of the ferrule 110 and at least a part of a mating regionof the front end surface 111 of the ferrule 110 mating with a matingferrule (not shown), so that the front end surfaces of the opticalfibers 102 and the at least a part of the mating region of the front endsurface 111 of the ferrule 110 are isolated from external environment.

The ferrule assembly 1000 shown in FIG. 1 and FIG. 2 is an independentassembly separated from the outer housing 300 (see FIG. 8) of theoptical fiber connector; and the outer housing 300 of the optical fiberconnector and the outer tail tube 400 can be fitted over the ferruleassembly 1000 shown in FIG. 2.

Continued with reference to FIG. 1 and FIG. 2, an annular seal ring 161is fitted over the sleeve 160. Specifically, an annular positioningrecess is formed in the sleeve 160, and the annular seal ring 161 isarranged in the positioning recess.

Continued with reference to FIG. 1 and FIG. 2, the multi-hole ferrule110 is a male ferrule, and the ferrule assembly 1000 further comprisesan alignment pin 120 mating with a alignment hole in a female ferrule,the alignment pin 120 is fitted in a mounting hole of the multi-holeferrule 110 and projecting from a front end of the multi-hole ferrule110.

However, the present disclosure is not limited to the illustratedembodiments, the multi-hole ferrule may be a female ferrule, and analignment hole is formed in the female ferrule to mate with an alignmentpin 120 of a male ferrule 110.

FIG. 6 is a schematic exploded view showing the inner housing of theferrule assembly shown in FIG. 1; and FIG. 7 is an assembly diagramshowing the inner housing of the ferrule assembly shown in FIG. 1.

As shown in FIGS. 1-2 and FIGS. 6-7, the inner housing 150 comprises afirst half-housing 150 a and a second half-housing 150 b which areseparated from each other and are capable of being assembled together.

As shown in FIGS. 6-7, the first half-housing 150 a and the secondhalf-housing 150 b are assembled together through a first snappingmechanism. In the illustrated embodiment, the first snapping mechanismcomprises: a first elastic snapping buckle 152 b formed on one of thefirst half-housing 150 a and the second half-housing 150 b; and a firstsnapping recess 152 a formed in the other one of the first half-housing150 a and the second half-housing 150 b.

Continued with reference to FIGS. 6-7, two first positioning features,which cooperate with each other for preventing the first half-housing150 a and the second half-housing 150 b from being assembled together ina misalignment state, are formed on the first half-housing 150 a and thesecond half-housing 150 b, respectively. In the illustrated embodiment,the first positioning features comprises: a first positioning protrusion153 b formed on one of the first half-housing 150 a and the secondhalf-housing 150 b; and a first positioning recess 153 a formed on theother one of the first half-housing 150 a and the second half-housing150 b.

FIG. 14 is a schematic enlarged view showing the ferrule protection capand the multi-hole ferrule shown in FIG. 1; and FIG. 15 is a schematicdiagram showing an operation of assembling the ferrule protection capand the multi-hole ferrule shown in FIG. 1.

As shown in FIGS. 1-2 and FIGS. 14-15, the ferrule protection cap 190comprises: a block like body portion 191 including the mating endsurface 195 mating with the front end surface 111 of the ferrule 110;and the elastic tail portion 192 connected to a side of the body portion191 opposite to the mating end surface 195 and extending by apredetermined length in the direction of axis of the optical fibers.

As shown in FIGS. 14-15, a receiving recess 193 is formed in the matingend surface 195 of the ferrule protection cap 190, so that when theferrule protection cap 190 is fitted over the front end surface 111 ofthe ferrule 110, the front end surfaces of the optical fibers 102, whichprotrude from the front end surface 111 of the ferrule 110, arehermetically received within the receiving recess 193.

In one embodiment of the present disclosure, as shown in FIGS. 14-15,the front end surface 111 of the ferrule 110 is formed at apredetermined angle to axes of the optical fibers, and the mating endsurface 195 of the ferrule protection cap 190 is formed at an anglecomplementary to that of the front end surface 111 of the ferrule 110.

In the illustrated embodiment, the ferrule 110 is a male ferrule, andthe mating end surface 195 of the ferrule protection cap 190 is formedtherein with an assembling hole 194 for mating with the alignment pin120 of the male ferrule. However, the present disclosure is not limitedto the illustrated embodiments, and the ferrule may be a female ferrule.When the ferrule is a female ferrule, the mating end surface of theprotection cap is formed thereon with a projecting assembling pin formating with an alignment hole of the female ferrule.

As shown in FIGS. 14-15, the elastic tail portion 192 of the ferruleprotection cap 190 is a corrugated elastic component. However, thepresent disclosure is not limited to this, the elastic tail portion 192of the ferrule protection cap 190 may also be an elastic component inthe form of a spring or an elastic component in the form of an elasticsheet.

FIG. 3 is a schematic exploded view showing a traction assemblyaccording to one exemplary embodiment of the present disclosure; FIG. 4is an assembly diagram showing a traction assembly according to oneexemplary embodiment of the present disclosure; and FIG. 5 is apartially cross sectional view of the traction assembly shown in FIG. 4,showing the ferrule protection cap.

As shown in FIG. 3 to FIG. 5, there is disclosed a traction assembly,comprising: a ferrule assembly 1000 according to any one of the aboveembodiments; and a traction component 200, which is hermeticallyconnected to the ferrule assembly 1000, seals the ferrule 110 of theferrule assembly 1000 therein, and is used to tow the ferrule assembly1000 through a pipe.

In one embodiment of the present disclosure, when the traction component200 is hermetically connected to the ferrule assembly 1000, the tractioncomponent 200 holds the ferrule protection cap 190 of the ferruleassembly 1000 on the ferrule 110 so as to prevent the ferrule protectioncap 190 from being disengaged from the ferrule 110 when the ferruleassembly 1000 is towed through the pipe. As shown in FIG. 5, the elastictail portion 192 of the ferrule protection cap 190 has a relative longlength, and thus, when the traction component 200 is hermeticallyconnected to the ferrule assembly 1000, an inner wall of the tractioncomponent 200 is pressed against the elastic tail portion 192 of theferrule protection cap 190 so as to elastically hold the ferruleprotection cap 190 over the ferrule 110.

In the illustrated embodiment, the traction component 200 is threaded onthe inner housing 150 of the ferrule assembly 1000; and when thetraction component 200 is threaded on the inner housing 150 of theferrule assembly 1000, an annular seal ring 161 over the sleeve 160 ofthe ferrule assembly 1000 is pressed by the traction component 200 so asto seal an interface between the traction component 200 and the ferruleassembly 1000.

As shown in FIGS. 3-5, the traction component 200 is a cylindricalcomponent having a closed end and an open end, and the cylindricalcomponent is fitted over the inner housing 150 of the ferrule assembly1000.

As shown in FIGS. 3-5, an external thread 151 is formed on an outer wallof the inner housing 150 of the ferrule assembly 1000, and an internalthread 251 is formed on an inner wall of the traction component 200 andconfigured to be connected with the external thread 151.

As shown in FIGS. 3-5, a connection portion 210 is formed on an outerside of the closed end of the traction component 200 and connected witha traction rod or a traction cord, so that the traction assembly 1000 isdriven through the pipe by pulling or pushing the traction rod or thetraction cord.

As shown in FIGS. 3-5, the inner wall of the traction component 200 ispressed against the elastic tail portion 192 of the ferrule protectioncap 190, so that the ferrule protection cap 190 is elastically held overthe ferrule 110.

As shown in FIGS. 3-5, the outer diameter of the traction component 200is substantially the same as that of thermal shrinkable tube 180,thereby reducing the outer diameter dimension of the whole tractionassembly as small as possible.

FIG. 8 is a schematic exploded view showing an optical fiber connectoraccording to one exemplary embodiment of the present disclosure; FIG. 9is a schematic diagram showing a snapping mechanism between an outerhousing and the inner housing of the optical fiber connector shown inFIG. 8; and FIG. 10 is a schematic diagram showing a state in which theferrule protection cap of the ferrule assembly passes through areceiving hole of the outer housing of the optical fiber connector shownin FIG. 8.

As shown in FIGS. 8-10, an annular seal ring 161 is fitted over thesleeve 160 so that when the outer housing 300 of the optical fiberconnector is fitted on the ferrule assembly 1000, the annular seal ring161 is pressed by the outer housing 300 of the optical fiber connector,thereby sealing an interface between the outer housing 300 of theoptical fiber connector and the ferrule assembly 1000.

As shown in FIGS. 8-10, the inner housing 150 and the outer housing 300are assembled together through a second snapping mechanism. In oneembodiment, the second snapping mechanism comprises: a second elasticsnapping buckle 354 formed on one of an outer wall of the inner housing150 and an inner wall of the outer housing 300; and a second snappingrecess 154 formed in the other one of the outer wall of the innerhousing 150 and the inner wall of the outer housing 300.

As shown in FIGS. 8-10, two second positioning features, which cooperatewith each other for preventing the inner housing 150 and the outerhousing 300 from being assembled together in a misalignment state, areformed on the outer wall of the inner housing 150 and the inner wall ofthe outer housing 300, respectively. In one embodiment, the secondpositioning features comprise: a second positioning protrusion 155formed on one of the outer wall of the inner housing 150 and the innerwall of the outer housing 300; and a second positioning recess 355formed in the other one of the outer wall of the inner housing 150 andthe inner wall of the outer housing 300.

FIG. 11 is a schematic diagram showing a positioning structure forpreventing an error mounting between an inner housing and an outerhousing of a female connector; and FIG. 12 is a schematic diagramshowing a positioning structure for preventing an error mounting betweenan inner housing and an outer housing of a male connector.

The optical fiber connector may be a female connector shown in FIG. 11or a male connector shown in FIG. 12, and the second positioning featureof the female connector mismatches with the second positioning featureof the male connector so as to prevent the outer housing 300′ of themale connector from being mounted on the inner housing 150 of the femaleconnector in error, or to prevent the outer housing 300 of the femaleconnector from being mounted on inner housing 150′ of the male connectorin error.

As shown in FIG. 11 and FIG. 12, dimensions, number and shapes of thesecond positioning features of the female connector may be differentfrom those of the second positioning features of the male connector. Forexample, the second positioning features of the female connector 300shown in FIG. 11 comprise one positioning protrusion 155 and onepositioning recess 355 mating with each other, while the secondpositioning features of the female connector 300′ shown in FIG. 12comprise two positioning protrusions 155′ and two positioning recesses355′ mating with the two positioning protrusions. In addition,dimensions and shapes of the positioning protrusion 155 and thepositioning recess 355 shown in FIG. 11 are different from those of thepositioning protrusions 155′ and positioning recesses 355′ shown in FIG.12.

FIG. 13 is a partially cross sectional view of an assembled opticalfiber connector according to one exemplary embodiment of the presentdisclosure, showing the ferrule protection cap.

As shown in FIGS. 11-13, a receiving hole 390 for mating with theferrule 110 is formed in the outer housing 300 of the optical fiberconnector; and the ferrule protection cap 190 is configured to becapable of passing through the receiving hole 390 of the optical fiberconnector. In one embodiment of the present disclosure, a dimension ofthe ferrule protection cap 190 in a direction perpendicular to the axesof the optical fibers is smaller than that of the ferrule 110 in thedirection perpendicular to the axes of the optical fibers.

As shown in FIGS. 11-13, when the outer housing 300 of the optical fiberconnector is fitted on the ferrule assembly 1000, the elastic tailportion 192 of the ferrule protection cap 190 extends out of the outerhousing 300 so as to facilitate removal of the ferrule protection cap190 after the outer housing 300 is fitted on ferrule assembly 1000. Inthe illustrated embodiment, the ferrule protection cap 190 is assembledonto the front end surface 111 of the ferrule 110 by a shaft-holefitting. Thus, the ferrule protection cap 190 can be easily removed fromthe ferrule 110.

According to a further general inventive concept of the presentinvention, there is provided a method of assembling an optical fiberconnector, comprising steps of:

providing a ferrule assembly 1000 according to any one of theembodiments described above; and

fitting the outer tail tube 400 and the outer housing 300 on the ferruleassembly 1000.

According to a further general inventive concept of the presentinvention, there is provided a method of assembling an optical fiberconnector on site, comprising steps of:

providing a traction assembly as described above;

towing the traction assembly through an elongated pipe;

removing the traction component 200 from the ferrule assembly 1000; and

fitting the outer housing 300 and the outer tail tube 400 of the opticalfiber connector on the ferrule assembly 1000, thereby forming anintegrated optical fiber connector.

According to a further general inventive concept of the presentinvention, there is provided an optical fiber connector, comprising anintegrated ferrule assembly 1000 formed by assembling a plurality ofcomponents together, and an integrated outer housing assembly 2000formed by assembling a plurality of components together. The ferruleassembly 1000 is adapted to be fitted in housing assembly 2000. Theintegrated ferrule assembly 1000 at least comprises the followingcomponents: an inner housing 150; a spring 140 mounted in the innerhousing 150; a multi-hole ferrule 110 mounted on a front end of theinner housing 150 and compressing the spring 140; a multi-fiber opticalcable 101 with an end thereof inserted into the inner housing 150 from arear end of the inner housing 150, a plurality of optical fibers 102 atthe end being fixed in a plurality of through holes of the ferrule 110;a sleeve 160 mounted on the rear end of the inner housing 150 andcooperating with the inner housing 150 to fix a strengthening element103 which is located at one end of the cable 101 on the rear end of theinner housing 150; and a thermal shrinkable tube 180 thermally shrunkover the sleeve 160 and a section of the cable 101 exposed from thesleeve 160. The integrated outer housing assembly 2000 at leastcomprises the following components: an outer housing 300; an outer tailtube 400 connected to a rear end of the outer housing 300; and an outerprotection cap 500 hermetically connected to a front end of the outerhousing 300.

FIG. 16a is a schematic exploded view showing a housing assembly 2000 ofa female connector 10; FIG. 16b is an assembly diagram showing thehousing assembly 2000 of the female connector 10; FIG. 17a is aschematic diagram showing the ferrule assembly 1000 and the housingassembly 2000 of the female connector 10; and FIG. 17b is an assemblydiagram showing the female connector 10 formed by assembling the ferruleassembly 1000 and housing assembly 2000 shown in FIG. 17 a.

As shown in FIG. 16a and FIG. 16b , in the illustrated embodiment,components such as the outer housing 300, the outer tail tube 400, theouter protection cap 500, a seal ring 700 and the like can bepreassembled into an integrated outer housing assembly 2000.

In one embodiment of the present disclosure, the outer tail tube 400 isfitted over the rear end of the outer housing 300. An external thread310 is formed on an outer wall of the frond end of the outer housing300, and an internal thread (not shown) is formed on an inner wall ofthe outer protection cap 500. The outer protection cap 500 is threadedon the outer wall of the front end of the outer housing 300, and theseal ring 700 is pressed between the outer protection cap 500 and theouter housing 300, thereby sealing an interface between the outerprotection cap 500 and the outer housing 300. As such, the outerprotection cap 500 is hermetically connected to the front end of theouter housing 300.

As shown in FIG. 17a and FIG. 17b , in the illustrated embodiment, sincecomponents such as the outer housing 300, the outer tail tube 400, theouter protection cap 500 and the like can be preassembled into anintegrated outer housing assembly, a worker only needs to insert theintegrated ferrule assembly 1000 into the integrated outer housingassembly 2000 on site, in such a way, the assembling operation of thewhole optical fiber connector is completed conveniently without fittingthe components, such as the outer housing 300, the outer tail tube 400,the outer protection cap 500 and the like, on the integrated ferruleassembly 1000 one by one on site, thereby improving assemblingefficiency.

FIG. 18a is a schematic exploded view showing a housing assembly 2000′of a male connector 10′; FIG. 18b is an assembly diagram showing thehousing assembly 2000′ of the male connector 10′; FIG. 19a is aschematic diagram showing the ferrule assembly 1000′ and the housingassembly 2000′ of the male connector 10′; and FIG. 19b is an assemblydiagram showing the male connector 10′ formed by assembling the ferruleassembly 1000′ and housing assembly 2000′ shown in FIG. 19 a.

As shown in FIG. 18a and FIG. 18b , in the illustrated embodiment,components, such as an outer housing 300′, an outer tail tube 400′, anouter protection cap 500′, a screw nut 600′, a seal ring 700′ and thelike, are preassembled into an integrated outer housing assembly 2000′.

In one embodiment of the present disclosure, the outer tail tube 400′ isfitted over a rear end of the outer housing 300′. The screw nut 600′ isfitted over the outer housing 300′. An external thread 510′ is formed onan outer wall of the frond end of the outer housing 300′, and aninternal thread 610′ is formed on an inner wall of the screw nut 600′.The screw nut 600′ and the outer protection cap 500′ are threaded witheach other, and the seal ring 700′ is pressed between the outerprotection cap 500′ and the outer housing 300′, thereby sealing aninterface between the outer protection cap 500′ and the outer housing300′. In such a way, the outer protection cap 500′ is hermeticallyconnected to the front end of the outer housing 300′.

As shown in FIG. 19a and FIG. 19b , in the illustrated embodiment, sincecomponents such as the outer housing 300′, the outer tail tube 400′, theouter protection cap 500′, the screw nut 600′, the seal ring 700′ andthe like can be preassembled into an integrated outer housing assembly2000′, a worker only needs to insert the integrated ferrule assembly1000′ into the integrated outer housing assembly 2000′ on site, in sucha way, the assembling operation of the whole optical fiber connector iscompleted conveniently without fitting the components such as the outerhousing 300′, the outer tail tube 400′, the outer protection cap 500′,the screw nut 600′, the seal ring 700′ and the like on the integratedferrule assembly 1000′ one by one on site, thereby improving assemblingefficiency.

According to a further general inventive concept of the presentinvention, there is provided a method of assembling an optical fiberconnector on site, comprising steps of:

providing the ferrule assembly 1000 as shown in FIG. 2;

providing the traction component 200 and hermetically connecting thetraction component 200 to the ferrule assembly 1000 so as to seal theferrule 110 of the ferrule assembly 1000 within the traction component,as shown in FIG. 3 and FIG. 4;

passing the ferrule assembly 1000 through an elongated pipe by towingthe traction component 200;

removing the traction component 200 from the ferrule assembly 1000;

providing the housing assembly 2000 as shown in FIG. 16; and

fitting the ferrule assembly 1000 into the housing assembly 2000,thereby forming an integrated optical fiber connector 10, as shown inFIG. 17.

Although the present disclosure has been described in conjunction withthe attached drawings, the embodiments shown in the drawings areintended to exemplarily illustrate preferred embodiments of the presentinvention, and should not be interpreted as being limitative to thepresent invention.

Although several exemplary embodiments of the general inventive concepthave been shown and described, it would be appreciated by those skilledin the art that various changes or modifications may be made in theseembodiments without departing from the principles and spirit of thepresent invention, the scope of which is defined in the claims and theirequivalents.

It should be noted the term “comprise” does not exclude other elementsor steps, and the term “a” or “an” does not exclude more than onecomponent. Further, any reference number in claims should be interpretedas being limitative to the scope of the present invention.

What is claimed is:
 1. An optical fiber connector assembly, comprising:a first pre-assembled subassembly, including: an inner housing extendingfrom a rear end to a front end and including a first snapping component;a sealing component positioned around the inner housing; a springmounted in the inner housing; and a ferrule positioned forward of thespring and compressing the spring; and a second pre-assembledsubassembly, including: an outer housing, the outer housing including asecond snapping component; wherein the second pre-assembled subassemblyis adapted to be rearwardly sleeved over the first pre-assembledsubassembly such that the first and second snapping components snaptogether and the sealing component is pressed between the outer housingand the first pre-assembled subassembly to provide a sealing interfacebetween the second pre-assembled subassembly and the first pre-assembledsubassembly.
 2. The optical fiber connector assembly of claim 1, whereinthe first pre-assembled subassembly includes a sleeve mounted on therear end of the outer housing; and wherein the sealing component ispositioned over the sleeve.
 3. The optical fiber connector assembly ofclaim 2, wherein the sealing component is an annular seal ring that ispositioned in an annular recess defined by the sleeve.
 4. The opticalfiber connector assembly of claim 1, wherein the first snappingcomponent includes one of: i) a recess on an outer wall of the innerhousing; or ii) a buckle on the outer wall of the inner housing; andwherein the second snapping component includes the other of the recessand the buckle on an inner wall of the outer housing.
 5. The opticalfiber connector assembly of claim 1, wherein the ferrule is amulti-fiber ferrule.
 6. The optical fiber connector assembly of claim 2,wherein the first-pre-assembled subassembly includes a thermally shrunktube shrunk over the sleeve and a section of a cable having opticalfibers supported by the ferrule.
 7. The optical fiber connector assemblyof claim 1, wherein the inner housing includes a first half-housing anda second half-housing that are assembled together.
 8. A method ofassembling an optical fiber connector, comprising the steps of: a)assembling a first subassembly including an inner housing extending froma rear end to a front end and having a first snapping component, asealing component positioned around the inner housing, a spring mountedin the inner housing, and a ferrule positioned forward of the spring andcompressing the spring; and b) subsequent to the step a), rearwardlysleeving a second subassembly including an outer housing having a secondsnapping component over the first subassembly such that the first andsecond snapping components snap together and the sealing component ispressed between the outer housing and the first pre-assembledsubassembly to provide a sealing interface between the secondpre-assembled subassembly and the first pre-assembled subassembly. 9.The method of claim 8, further comprising, subsequent to the step a) andprior to the step b), passing the first subassembly through an elongatedpipe.
 10. The method of claim 9, wherein the passing includes towing thefirst subassembly using a traction component.
 11. The method of claim10, further comprising, prior to the step b), removing the tractioncomponent from the first subassembly.
 12. The method of claim 9, whereinthe passing includes pulling or pushing the first subassembly throughthe elongated pipe.
 13. An optical fiber connector assembly, comprising:a pre-assembled subassembly, including: an inner housing extending froma rear end to a front end; a sealing component positionedcircumferentially around an outer wall of the inner housing; a springmounted in the inner housing; and a ferrule positioned forward of thespring and compressing the spring; and an outer housing including a wallhaving a thread located on an outer wall of the outer housing andconfigured to threadably receive a protection cap; wherein the outerhousing is adapted to be rearwardly sleeved over the pre-assembledsubassembly to assemble the pre-assembled subassembly and the outerhousing together such that the outer wall of the inner housing engagesan inner wall of the outer housing and such that the sealing componentis pressed between the outer housing and the pre-assembled subassemblyto provide a sealing interface between the outer housing and thepre-assembled subassembly.
 14. The optical fiber connector assembly ofclaim 13, further comprising a protection cap threaded on the thread ofthe outer housing.
 15. The optical fiber connector assembly of claim 13,wherein the sealing component is an annular seal ring that is positionedin an annular recess.
 16. The optical fiber connector assembly of claim13, wherein the ferrule is a multi-fiber ferrule.
 17. The optical fiberconnector assembly of claim 13, further comprising a screw nut.
 18. Theoptical fiber connector assembly of claim 17, wherein the screw nut isfitted over the outer housing.
 19. A method of assembling an opticalfiber connector, comprising the steps of: a) assembling a subassemblyincluding an inner housing extending from a rear end to a front end andhaving an annular seal ring positioned circumferentially around an outerwall of the inner housing, a spring mounted in the inner housing, and aferrule positioned forward of the spring and compressing the spring; b)subsequent to the step a), rearwardly sleeving an outer housing over thesubassembly such that the outer wall of the inner housing engages aninner wall of the outer housing and such that the annular seal ring ispressed between the outer housing and the subassembly to provide asealing interface between the outer housing and the subassembly; and c)threading a screw cap onto a thread of the outer housing, the threadbeing located on an outer wall of the outer housing.
 20. The method ofclaim 19, further comprising, subsequent to the step a) and prior to thestep b), passing the subassembly through an elongated pipe.
 21. Themethod of claim 20, wherein the passing includes towing the subassemblyusing a traction component.
 22. The method of claim 20, wherein thepassing includes pulling or pushing the subassembly through theelongated pipe.